Chapter 4 - Molecules and Compounds Flashcards
What are the 3 types of chemical bonds?
covalent, ionic, metallic
What are covalent bonds?
non metal reacting with non metal
sharing of electrons
lower melting and boiling point
What are Ionic bonds?
metal reacting with non metal
transfer of electrons
higher melting point and boiling point
What are metallic bonds?
metals bonding together
What is the Empirical formula?
relative number of each atom (e.g. CH)
What is the molecular formula?
the actual number of each atom (e.g. C6H6) (Benzene)
What are Lewis Dot structures?
simple way to depict the valence electrons in an atom, product reactivity and structure of compounds (represented by dots of electrons in outer shells)
What is the Octet rule?
atoms tend to gain, lose or share electrons until they have a full outer shell
In Ionic bonding which elements lose electrons? to form what?
Alkali and alkaline earth metals due to low ionisation energy
form cations
In ionic bonding which elements gain electrons? to form what?
Halogens - have a high electron affinity
form anions
What is lattice energy?
stabilisation that accompanies the formation of the crystal lattice
heat released when the solid crystal forms from separate ions in the gas state
always exothermic
What can lattice energy be calculated by?
is hard to measure directly, can be calculated by Born-Haber cycle
What are the steps to naming a binary ionic compound where metal has only 1 possible charge?
- full name of cation (metal)
- add ‘ide’ to anion (non metal)
How do you name an ionic compound where metal has multiple charges?
1.full name of cation
2. charge of cation (represented in roman numerals in brackets) (e.g. Pb (IV) … )
3. add ‘ide’ to anion
Polyatomic Ions need to be memorised; what is C2H3O2^-
Acetate
